Method and means for drying components in the making of asphalt



P 1962 w. WRIGHT 3,054,193 METHOD AND MEANS FOR DRYING COMPONENTS IN THE MAKING OF ASPHALT Filed Nov. 5, 1959 2 Sheets-Sheet 1 INVENTOR. n m

Q Q l E m BY WILBUR WRIGHT l/M1 7. I

ATTO E Y p 1962 w. WRIGHT 3,054,193

METHOD AND-MEANS FOR DRYING COMPONENTS IN THE MAKING OF ASPHALT Filed Nov. 5, 1959 2 Sheets-Sheet 2 INVENTOR. l N WILBUR WRIGHT g 1 5 BY 344mm! 7 1 I ATT NEY METHOD AND MEANS FOR DRYING COMPO- NENTS IN THE MAKING OF ASPHALT Wilbur Wright, 3800 Wood St., Lansing, Mich. Filed Nov. 3, 1959, Ser. No. 850,605 11 Claims. (Cl. 34-31) This invention relates primarily to the paving industry and particularly to asphalt paving, however it may be used in any industry, where it is necessary to dry ore, stone, aggregates, and the like, during an industrial operation.

An object of the invention is to improve driers, such as disclosed in my co-pending application, Serial No. 761,871, filed September 18, 1958, of which this application may be considered a continuation in part. It is, therefore, an object of the invention to improve industrial drying methods, particularly in the making of asphalt, by the separation of the sand from the aggregates during the drying operation. It is well known that the aggregates heat more slowly than the sand.

A further object of the invention is to provide a drier mechanism, which is simple in construction, economical to manufacture and efficient in operation.

Another object of the invention is to provide a drier, which is constructed and arranged so that the combustion cycle of the drier may be regulated and controlled, to the end that large, or small, batches of components, may be handled effectively and economically in the same drier.

Another object of the invention is to provide a drier for use in making asphalt, in which the air intake and exhaust of the drier are regulated and controlled, to the end that a greatly improved end product results.

Another object of the invention is to provide a drier, which is constructed and arranged, so that the drier can be shortened, in effect, whereby the heat may be con centrated in a smaller area.

Another object of the invention is to provide a device of the character indicated, which is constructed and arranged, so that theaggregates are separated from the sand, whereby the aggregates may receive the direct and concentrated heat from the combustion unit.

Another object of the invention is to provide a drier which is constructed and arranged so that the aggregates and sand may be handled separately in the drying operation, with a greatly reduced amount of fuel.

Another object of the invention is to provide a device of the character indicated which is constructed and arranged so that the air flow may be varied, as the combustion changes, whereby proper balance may be maintained between the operating temperatures and the air volume.

Another object of the invention is to provide a drier, in which the combustion unit may be moved longitudinally into and out of the drier, which in eifect changes the length of the drier drum, effects an economy in the fuel consumption, and assists in maintaining a proper,

temperature in the drier, to compensate for changes in weather, relatively high humidity in the atmosphere, and variable amounts of residual moisture in the aggregate I and sand mixture. A

In the making of asphalt, the viscosity of the end prodnot is all important. Viscosity is determined by the temperature control of ingredients during the mixing operai tion. The sand and the aggregates absorb heat at a much different rate. The aggregates, because of their size and bulk, heat more slowly than the sand. The ideal temperature for sand is approximately 200 F., and the ideal temperature for the aggregates is approximately 450 F. I have found, therefore, that separating the sand from the aggregates, and subjecting the two components to diifer- :tially on the line 5-5 of FIG. 1.

Patented Sept. 18, 1962 ice percent from that used in conventional methods. This greatly reduces the amount of moisture formed, as the result of the combustion operation, as the free hydrogen resulting from the combustion operation will then have less oxygen to combine with. Less steam will be discharged from the drier, and there will be much less overall moisture, to be disposed of during the drying operation.

Further than that, the reduced air intake causes much less agitation of dust within the drier, and enables me to better collect and handle the dust, and use it in the subsequent mixing operation, instead of wasting it by discharging it intov the atmosphere. It is obvious therefore, that my method is also cleaner and less apt to result in air pollution, which is always a problem with conven tional methods. f

In practicing my invention, I may control and vary the air intake in several ways, such as by placing dampers in the outlet stacks, or by using variable motors on the fans. I prefer to use dampers, however, as their control is more easily effected.

shown in FIG. 1.

FIG. 3 is a right end elevational view of the device shown in FIG. 1.

FIG. 4 is a section taken substantially on the line 4-4 of FIG. 1.

FIG. 5 is an enlarged detail, in section talsen substan- FIG. 6 is a section taken substantially on the line 66 of FIG. 1.

itrated in FIG. 7.

FIG. 9 is a right end elevational view of the device 5 illustrated in FIG. 7.

will be understood that in the embodiment herein dis- Referring now more particularly to the drawing, it

closed, the reference character 11 indicates, in general, a hollow cylindrical member, which is made of heat and abrasive resisting metal, suitable to withstand the ravages of high temperatures and the abrading action of sand and heavy aggregates. The cylinder 11 rotates on trunnions 1 device may be transported from place to place as more cross frame members (not shown). The frame is preferably supported by wheels (not shown), so that the j fully described in my co-pending application hereinabove referred to. The trunnions 12 engage track members 14 which encircle the cylinder 11.

.. ent drying conditions, enables me to better control the and aggregates are loaded into the charging end 15, by

means of a conveyor belt 17, or other suitable means. The loading end 15 has an end closure member 18, which comprises a sheet metal housing, in which is contained the dust collecting apparatus, which I will describe 'rnore particularly hereinafter. The housing 18 is secured in position by means of supporting members 19 and 20, which are secured by any suitable means to the frame members 13. The discharge end of the cylinder 16, is glosed by means of a firewall 21, and a combustion unit 22, which will be described more particularly hereinafter. The combustion hnit 22 is mounted on a frame member 23, which moves longitudinally on rollers 24, which are mounted for rotation in suitable brackets 25, which are supported by the structural members 26 and 27, which in turn are secured to the frame members 13, by any suitable means, as shown in FIG. 3. The frame member 23 is held down by means of rollers 28, which permit the frame 23 to move longitudinally into and out of the cylinder 11, but which prevent the frame 23 from being displaced upwardly. Suitable stops 29, limit the longitudinal movement of the frame 23. The end members 18 and 21 are fixed against rotation and are spaced, as at 30 and 31, from the rotating cylinder 11 to provide air seals, which air seals permit the siphoning of air into the cylinder 11 when the device is in operation, and prevents the escape of air from the cylinder when the device is being used. At the charging end 15 of the cylinder a receiving compartment 32 is formed, which compartment is provided with baffles 33, which lift and tumble the mixture of sand and aggregates, which is received by the cylinder 11 from the conveyor belt 17. A compartment 34 is formed at the discharge end of the cylinder 11, which compartment is provided with baffles 35, which tumble and lift the sand and aggregates and re-mix them, after they have passed through the cylinder 11 as hereinafter described. The re-mixed sand and aggregates are discharged from the compartment 34 through the discharge chute 36, which deposits the re- :i'ni'ited components in a mixing chamber (not shown), in which the hot sand and aggregates are mixed with the hot bituinin in the asphalt plant as in conventional practice. I

One of the features of this invention resides in the particular construction and arrangement of the interior of 'the cylinder 11, which I 'will now describe. It will be noted in FIG. 1, that the cylinder 11 has an outer wall 112: and an inner wall 11b which walls are spaced, as shown in FIGv l, to define a sand compartment 37. The inner wall 111) defines a smaller in diameter cylindrical compartment 38, in which is received the aggregates as hereinafter described. The walls 11a and 11b are both provided with a plurality of lifts, or flights 39 and 40, which lift and tumble the sand and aggregates as in conventional practice. The walls 11a and 11b are held in spaced relation by means of rivets 41, or other suitable means. The spaced walls 11a and 11b are joined together, near the loading end 15, by means of screens 42, which are welded, or otherwise secured, to the spaced walls 11a and 11b. In FIG. 1, I illustrate the screens 42 positioned angularly, with respect to the walls 11a and 11b, although they may also be positioned in parallel relation with the walls, with very little structural change. In either 'event, the screens 42 are of such 'size mesh, that they permit the sand received from the conveyor belt 17 and the loading compartment 32, to pass through them and be received in the sand compartment 37, in which compartment it will travel from the loading end 15, to the discharge end 16 of the cylinder 11. On the other hand, the aggregates received in the mixture from the conveyor belt 17 and the loading compartment 32, being too large topass through the mesh of the screen 42, will move into the aggregate compartment 38, through which they will travel from the charging end 15 to the discharge end 16 of the cylinder. Thus it will be seen that I have devised an apparatus for separating the sand from the aggregates, as the said materials pass through the drier cylinder. After the sand and aggregates in the separate compartments 37 and 38 have been thoroughly dried by the combustion unit 22, they come together and are again remixed in the compartment 34, from which they are discharged through the chute 36.

The combustion unit 22 consists of a burner 43, which is supplied with oil, as at 44, and is supplied with air by means of a blower 45. The combustion unit 22 has a refractory lining 46 and outer walls 221: and 22b, forming a space therebetween, through which fresh air is drawn to help keep the combustion unit 22 from becoming overheated. As previously described, the combustion unit 22 is longitudinally movable into and out of the cylinder 11. This in effect lengthens and shortens the cylinder 11, so that large and small batches of sand and aggregates may be dried with equal facility. It will be noted that the aggregate compartment 38 is centrally positioned in the cylinder 11, so that the aggregates, which are heavier and of greater mass, will receive the concentrated heat from the combustion unit 22. By the same token the sand compartment 37 is located in the outer and cooler portion of the cylinder, so that it receives less heat than is received by the aggregates.

The air which is forced into the cylinder 11 by means of the blower 45, and the air which is siphoned into the cylinder 11, between the spaced walls 22a and 22b, is of high velocity and greatly agitates the dust inside the cylinder 11, which dust is backed up and carried to the end 15 of the cylinder 11, where it is separated from the air, by means of the dust collectors housed in the member 18. The housing 18 contains a two stage dust collecting assembly, which incorporates a primary dust collector 47, and a secondary dust collector 48. The primary dust collector is made up of a plurality of tubes 47, one of which is illustrated in FIG. 6, and the secondary dust collector is made up of a plurality of concentrating tubes 48, one of which is illustrated in FIG. 5. The primary tubes 47 receive dust-laden air through the small ends 49, and through slits 50 (FIG. 6) formed in their walls, and the air moves through the tubes into the expansion chambers 51, from which the dust is discharged through openings 52 into the primary dust compartment 53 of the collector. The primary dust is removed through suitable conduits 54 and 55, which communicate with the discharge chute 36 at the opposite end of the cylinder. Approximately of the dust is removed from the air in the primary stage. The 90% clean air is discharged through the conduits 56, one of which is on each side of the housing 18. The conduits 56 communicate with the primary exhaust stack (not shown), which discharges the clean air to the atmosphere. Approximately 10% of the air, which travels through the primary collector tubes 47 and the primary dust collecting compartment 53, enters the secondary collector tubes 48, and the dust remaining in this air is dropped through the openings 57, into the secondary dust collector area 58, from which it is removed through the conduits 59 and 60, which also communicate with the discharge chute 36. The 10% of the air, which is divested of nearly all the remaining dust is discharged through the secondary air exhaust 5811.

A further feature of the invention is the regulation of the volume of air, which is permitted to enter the cylinder 11. I have considered various means for controlling the volume of air passing through the drier. I have considered variable motors for driving the air blower 45, and the blowers for removing the air through the exhaust conduits 56 and 58a. Controlling such variable motors offers certain difliculties. I, therefore, prefer to regulate the volume of air entering the cylinder 11, by controlling the amount of air, which is exhausted through the conduits 56 and 58a. In this embodiment I provide dampers 61, which may be in the form of venetian blinds, which may be opened and closed by suitable electric motors 61a, or other means, which are controlled by means of one or more thermo couples 62, which are electrically connected, as at 63, to recording pyrometers 64, which are carried on a remotely positioned panel 65, and are connected to a suitable source of electrical energy (not shown). I prefer to mount at least one thermo-couple in the primary exhaust conduit, so that I can get an accurate reading of the temperature developed inside the cylinder 11. One of the pyrometers 64 is connected to the actuating means 61:: for opening and closing the dampers 61 which means are arranged to open and close the dampers 61, when the proper temperature conditions exist in the cylinder. One of the thermo couples might also be positioned in the discharge chute 36, and elsewhere, at strategic locations, for indicating the temperatures therein and for regulating the opening and closing of the dampers 61. I do not intend to be restricted to any particular location for the thermo couple controls, for regulating the volume of air. In practicing my invention, the operating temperatures and the volumes of air to be used, would be predicated upon several factors, such as the outside temperature, the humidity, the amount of moisture in the aggregates and the sand, and other factors.

In FIG. 7, I show a modified form of the device, in which the combustion unit 22 is positioned in the loading end of the cylinder 11, instead of in the discharge end 16, as shown in FIG. 1. In this modified form the dust collector 65 is at the discharge end of the cylinder and is constructed in a more conventional manner. I illustrate the conventional dust collector 65, only for the purpose of locating it at the discharge end. It is within the contemplation of the invention to use the dust collector shown in FIG. 1 on the modified form of the invention illustrated in FIG. 7. In other respects the device would be constructed and would function as previously described.

It is believed that the operation of the device is obvious from the foregoing description.

What I claim and desire to secure by Letters Patent 1s:

1. The method of preparing components in the making of asphalt, which consists of flowing predetermined quantities of sand and aggregates through a drying cycle, maintaining said sand and said aggregates in separated imperforate compartments throughout said cycle, positioning said separated aggregates during said cycle, so that they will be subjected to the greatest heat, and during said cycle introducing controlled volumes of air to said sand and aggregates, whereby in effect to vary the capacity of said drying cycle.

2. The method defined in claim 1, in which the drying cycle is performed by heat generating means, positioned at the discharge end which are automatically responsive to the temperatures generated in said sand and aggregates.

3. A drier for use in the making of asphalt, comprising a rotatable cylinder having a charging end and a discharging end and having an imperforate outer wall and an imperforate inner wall, defining separated areas for respectively holding sand and aggregates, fine mesh screens connecting said walls at the charging end, and means for closing the ends of said cylinder, said means including a primary dust collector at the charging end, and a heat generator and blower at the discharge end.

4. The structure of claim 3, in which said heat generator and blower are moveable into and out of said cylin- 5 def t 5. The structure of claim 3, in which said dust collector is a two stage dust collector, comprising a plurality of horizontally positioned, graduated, tubular members.

6. The structure of claim 3, in which said discharge end closure member includes a longitudinally moveable combustion unit, there being heat responsive means associated with the discharge end of said cylinder for regulating said combustion unit.

7. The structure of claim 3, in which. said end closure means include a longitudinally moveable member for supporting the heat generator and blower, a primary and secondary dust collector, and charging and discharging members, there being air intake and exhaust means communicating with said cylinder, and heat responsive means associated with said air exhaust means for controlling said air intake and exhaust means.

8. A drier for an asphalt plant, comprising the combination of a rotatable cylinder, said cylinder having a charging end and a discharging end, spaced imperforate walls defining a continuous sand compartment and a continuous aggregate compartment in said cylinder, an end compartment in the charging end of said cylinder for receiving sand and aggregates, fine mesh screens connecting the said walls for separating the sand and aggregates, a compartment at the opposite end for re-mixing the separated sand and aggregates, combustion means, longitudinally moveable into and out of said cylinder, for heating the said sand and aggregate compartments, air intake and exhaust passways communicating with the interior of said cylinder, temperature responsive means at least in the exhaust passageway for actuating means controlling the volume of air entering said cylinder, and dust collecting means at one end of said cylinder for cleaning the air passing through said cylinder.

9. The structure of claim 8, including means for advancing the dust, taken from said collector, to the discharge end of said cylinder.

10. The structure of claim 8, in which said dust collecting means consist of a plurality of graduated tubes forming a primary compartment and a secondary compartment, which compartments are enclosed in a housing comprising an end closure member for said cylinder.

11. The structure of claim 8, in which said combustion means comprises at least part of an end closure member for said cylinder, said combustion means being supported on tracks Which extend well into one end of said cylinder.

References Cited in the file of this patent UNITED STATES PATENTS 1,058,342 White et al Apr. 8, 1913 1,206,918 Rosendahl Dec. 5, 1916 1,653,050 Lindhard Dec. 20, 1927 1,703,635 Ranson Feb. 26, 1929 1,960,085 Goldberg et a1. May 22, 1934 1,976,208 Agthe et al. Oct. 9, 1934 2,122,037 Lissaner June 28, 1938 2,309,810 West Feb. 2, 1943 2,339,207 Tyler Jan. 11, 1944 2,484,539 Walker Oct. 11, 1949 2,695,221 Klugh Nov. 23, 1954 2,841,385 Muller July 1, 1958 FOREIGN PATENTS 750,313 Great Britain June 13, 1956 

1. THE METHOD OF PREPARING COMPONENTS IN THE MAKING OF ASPHALT, WHICH CONSISTS OF FLOWING PREDETERMINED QUANTITIES OF SAND AND AGGREGATES THROUGH A DRYING CYCLE, MAINTAINING SAID SAND AND SIAD AGGREGATES IN SEPARATED IMPERFORATED COMPARTMENTS THROUGHOUT SAID CYCLE, POSITIONING SAID SEPARATED AGGREGATES DURING SAID CYCLE, SO THAT THEY WILL BE SUBJECTED TO THE GREATEST HEAT, AND DURING SAID CYCLE INTRODUCING CONTROLLED VOLUMES OF AIR TO SAID SAND AND AGGREGATES, WHEREBY IN EFFECT TO VARY THE CAPACITY OF SAID DRYING CYCLE. 